1. Field of the Invention
This invention relates to engine fuel supply systems having a fuel pump located in a fuel tank, and more particularly to a fuel delivery module that is located in a fuel tank for maintaining a sufficient level of fuel at the inlet of the fuel pump when the fuel tank fuel level is low or when vehicle operations cause the fuel tank fuel level to fall below the inlet of the fuel pump.
2. Description of the Related Art
Fuel tanks, particularly in automobiles, typically contain a fuel pump to supply fuel from the fuel tank to the engine. Generally, the fuel pump is mounted near the bottom of the fuel tank so that the inlet of the fuel pump is as near as possible to the lowest level in the tank so that a source of fuel will be available even when fuel level is low. Despite such a placement of the fuel pump inlet, events during vehicle operation, such as cornering, braking and acceleration can cause the fuel to "slosh" around, potentially uncovering the fuel pump inlet. Driving or parking on a slope could similarly result in the fuel pump inlet being uncovered. When the inlet is exposed, the fuel pump sucks air (or fuel vapor) causing the engine to stammer and stall. An additional problem occurs at engine start-up when fuel tank level is low and there is insufficient fuel at the pump inlet.
One solution to the above mentioned problems has been to place in the fuel tank a fuel reservoir that is replenished with fuel from the fuel tank and can provide fuel to the inlet of a fuel pump under certain operating conditions. For example, U.S. Pat. Nos. 5,341,842, 5,218,942 and 5,070,849 disclose modular fuel delivery systems wherein a portion of pressurized fuel from a fuel pump is routed to a jet pump that is used to entrain fuel from the fuel tank into a fuel reservoir to keep the fuel reservoir full of fuel in order to provide a source of fuel to the fuel pump at all times; U.S. Pat. No. 4,974,570 discloses a fuel supply system that includes a valve for conveying fuel from a reserve container to the fuel pump when a float valve in the tank closes due to a low level of fuel in the tank; and U.S. Pat. Nos. 5,642,719 and 5,363,827 disclose engine fuel systems wherein a fuel pump is located within a reserve fuel container that receives fuel from an engine return fuel line, and wherein a float operated valve opens a fluid path between the fuel pump and the reserve container when the fuel tank is near empty.
While each of the fuel supply systems disclosed in these patents may provide a solution to the aforementioned problems associated with a low fuel level in a fuel tank, they all have one significant disadvantage. Specifically, these systems all require the use of an engine fuel return line and therefore, are not generally suitable for use with a fuel injection system having only one fuel pipe leading between the fuel tank and the fuel injectors at the engine. These systems are conventionally known as "returnless" fuel systems, and an example of such a system can be found in U.S. Pat. No. 5,339,785.
In view of the increasing use of "returnless" fuel systems and the aforementioned problems with known fuel supply systems, there have been developments in fuel supply systems that include a fuel tank, a fuel reservoir in the fuel tank, a fuel pump in the fuel reservoir and a single fuel line for delivering fuel to an engine. For example, U.S. Pat. No. 5,692,479 discloses a returnless fuel delivery system that includes a fuel tank, a reservoir located within the fuel tank, and a fuel pump within the reservoir for pumping fuel to the engine via a single fuel line. The returnless fuel delivery system also includes a pressure regulator having an inlet port in fluid communication with the fuel pump, a first outlet port in fluid communication with the fuel line, and a second outlet port for returning excess low pressure fuel to the fuel reservoir. The system also includes a jet pump located between the second outlet port of the pressure regulator and the fuel reservoir. The excess fuel from the pressure regulator enters the jet pump and pressure is created at an orifice of the jet pump such that fuel is entrained from the fuel tank. The combined fuel (fuel from the jet pump and fuel entrained from the fuel tank) is then routed to the fuel reservoir.
While the fuel delivery system disclosed in U.S. Pat. No. 5,692,479 provides an advance in the field of modular fuel delivery systems for returnless fuel delivery systems, it does have certain disadvantages. For instance, the arrangement of the pressure regulator, the fuel filter and the jet pump in the fuel delivery system does not provide for ease of installation as the fuel filter is external to the fuel tank and the pressure regulator and the jet pump are external to the fuel reservoir.
Thus, there is a need for a fuel delivery module that can be located in a fuel tank for maintaining a sufficient level of fuel at the inlet of a fuel pump, that can be used with returnless fuel delivery systems, and that provides for an integrated arrangement of components such that the fuel delivery module can be installed in a fuel tank and placed in fluid communication with a single fuel line to an engine.